Black African nations demanded economic sanctions against South Africa in the Security Council yesterday as Western diplomats met privately with African envoys in an effort to avert a confrontation.

The American-led Western nations that have sought to negotiate a peaceful solution to the guerrilla war in Namibia had sought to avoid a Security Council debate on sanctions.

However, South Africa's apparent refusal two weeks ago to allow United Nations supervision of elections before NamKrisha Ramphul of Mauritius told the Security Council.

No matter what is said, there can be no doubt that South Africa is intent on an internal settlement to perpetuate its colonial rule in Namibia," Ambassador Radha Krisha Ramphul told the Security Council.

Of the trip by Seceretary of State Cyrus Vance and ministers of Britain, France, West Germany and Canada to South Africa two weeks ago, Ramphul said: "They have failed utterly."

The Africans have circulated a seven-page working paper that calls for trade and economic sanctions against Pretoria similar to those imposed by the United Naions against Rhodesia after. Ian Smith's government rebelled against sharing power with blacks.

The Western naions have countered with a draft that would censure South Africa for its decision to hold elections without outside supervision Dec. 14. The Western draft would declare these elections void, but would postpone any Security Council action until late December.

The Western strategy has been to gain more time in the hopes that South Africa will give new signs that it will honor its promise to hold elections under U.N. supervision next spring.

Vance and his fellow ministers concluded that South Africa has not ruled out eventual U.N. monitored elections, although several African states have taken Pretoria's decision to hold its own December elections as proof it has no intention of permitting interational supervision that could lead to an election won by the Southwest Africa People's Organization (SWAPO) which has been fighting a guerrilla war against South Africa in the Territory.

Africa support for U.S. led attempts to find a peaceful Namibia settlement has ebbed as African leaders have become suspicious that Washington was changing its African policy.

The Carter administration had won greater African support than its predecessors by its criticisms of South Africa's apartheid system and its efforts wo work in cooperation with the black Africa's apartheid system and its efforts to work in cooperation with the black African nations bordering South Africa and Namibia.

In the past the United States and other Western nations have vetoed African attempts to impose U.N. economic sanctions against South Africa where the Western nations have investments estimated at $20 billion.

Ambassador Artemon Simbananlye of Burundi, the chairman of the African group at the United Nations, urged Western nations to support sanctions this time.

"Recourse to the right of the veto would have no other meaning than complicity with [South Africa] which has been condemned by the entire international community," he told the Security Council.

The council will meet again this morning to hear scheduled speakers from six other nations in favor of sanctions. Meanwhile, efforts to draft a compromise resolution for formal submission to the council will continue.

It appeared likely that no resolution would be submitted until tomorrow or Friday at the earliest.

Namibia, formerly called Southwest Africa, has been ruled by neighboring South Africa under a League of Nations mandate since 1920, but the United Nations has called for Namibian independence for more than a decade.